Multipole magneto rotor charging block



Jan. 2, 1951 B. ROZETT 2,536,227

MULTIPOLE MAGNETO ROTOR CHARGING BLOCK Filed July 14, 1948 2 Sheets-Sheet 1 mww Jan. 2, 1951 ROZETT 2,536,227

MULTIPOLE MAGNETO ROTOR CHARGING BLOCK Filed July 14, 1948 2 Sheets-Sheet 2 Jef 271572 0Z6 5 M Patented Jan. 2, 1951 UNITED STATES ?AT4ENT OFFICE Benjamin Rozett, Chicago, Ill -assignor to Joseph Weidenhofl", Incorporated,a corporationof Iliinois Application July 14, 1948,"Serial No. 38,670

2 Claims. 1

This invention relates to inulti pole magneto rotor charging adapter blocks.

-'One feature of this invention is that it enables a-simple two-pole magnetizer, perfectly balanced magnetically, to recharge multi-pole magneto rotors, whether of an even or odd number of poles; another feature of this invention is that it ensures uniform ffiux :remnance, a very necessary characteristic in aiprop'erly charged rotor; another feature of the particular "blocks disclosed herewith is that pairs of fcooperating blocks are identical 'and .'can belm'ade with one casting; and yet another feature of this invention is that these particular blocks, "with the :pole portions at an angle to the plane of the :ioot portion, provide greater flux carrying -area and, with proper design, a minimum reluctance to flux flow. "Other features and advantages of this invention will be apparent from the :following specification and the drawings, in which:

Figure .1 is a side elevational view of a twopole ,magnetizer and a pair of blocks embodying my present inventions being used to charge a four-pole rotor; Figure 2 is a'top plan view of the structure shown in Figure vl; Figure 3 is a transverse sectional view 'al'ongthe line 3 -3 of Figure 1; Figure 4 is a side elevational ivie'w of one of the blocks, the left hand one "as viewed in Figure 1:; and Figure 5 is a sectional view along a plane through the rotor :axis, this view being along the line 5-5 of Figure 3.

In ignition circuits "for certain types of relatively high powered internal combustion engines there is an increasing trend toward mu lti pole rotors in the magnetos. craftengine of the radial type, fourteen cylinders are quite common, and if these are handled by a single magneto, the magneto must develop seven ignition impulses for each shaft rotation. This would obviously require an "unduly high rotor shaft speedof rotation when the engine is operating anywhere near its maximum speed, with very undesirable bearing and lubrication problems being presented in the magneto, if only a two-pole rotor were used. The use or a four-pole rotor cuts the required speed of rotation in halt, and such rotors are very common. Even a greater number of poles are frequently used.

Such rotors not only have to be charged initially, but also have to be relatively rreeuenuy chargedthroughouttheir :life, as aservi'c'e operaticn, to maintain the rotor ipole strength at the desired level. This has always heretofore been done .by mul-ti pole 'magnetizers having -the same .numberof wound poles as there "are poles in the In Fa high owered airrotor to be charged. Such magnetizers arerelativelyexpensive, because of the large amount of wire, ironan'd labor required to provide four or six wound poles of great strength, for example, but-also are extremely difiicult to properly balance magnetically with the precision desirable. Merely providing the same number of turnson each of the magnetizer coils by no means insures the same flux density in a given pole face area, since variations in the Winding, the ma'terialof the wire and pole piece enter into the balance. A two-pole magnetizer, on the other hand, is inherently perfectly balanced, since while it has two windings both contribute to a single magnetic circuit and the flux density in that portion of the magnetic circuit used for magnetizing-a rotor is a-summation of the contributions of the two coils, so that even substantial differences therein in no way disturb charging conditions.

In order to enable the relatively simple and inherently perfectly magnetically balanced twopole magnetizer to be used to charge multi-pole magneto rotors, I have devised adapter blocks having characteristics here disclosed. These blocks are of magnetic materialand each has a portion in good magnetic relationship with the faces of the poles of the magnetizer, each block further "having two pole port-ions adapted to receive the rotortherebetween, the pole portions of the two blocks being so constructed and arranged that they are interleaved and symmetrically spaced about the rotor during charging, with all portions of each block being spaced from all portions of the other block at least several times the spacing between the rotor and the adjacent-faces of the pole portions of the block to insure concentration of the flux into and through the rotor poles.

Referring now more particularly to the embodiment of the invention illustrated herewith, a "two pole magnetizer of a type now on the market is illustrated as having a base portion It, wound magnetizing coils It and I2, and pole pieces 13 and 14 providing pole faces 13c and Na in the same plane. During magnetizing procedure the coils would be energized from an appropriate source of current and strong magnetic forces of opposite polarity developed at the pole faces Mia and la, the poles and base oi course being of magnetic material, as cast steer. Further description of the magnetizer is believed unnecessary, as the particular device shown is available commercially and well known in the field.

Turning now more particularly to the adapter blocks, these are here identified in general as A and B. While identical devices in the particular form illustrated, it will be understood that they must always be used in pairs appropriate to the rotor size and number of poles, and that it is unnecessary that they be identical.

Since the particular embodiment of my inventions illustrated herewith has identical blocks, only one such block will be described in detail, except insofar as may be necessary to bring out the combined operation of the devices. Referring now more particularly to Figures 3, 4 and 5, it will be seen that the block A has a main body portion here identified as 20 carrying, or more properly speaking having integral therewith, the two pole portions 2| and 22. The size of the blocks is of course determined by the size, and particularly of the diameter, of the rotor to be charged, one pair of blocks which I have built and which are of representative size for conventional magneto rotors having body'portions 4 /2 inches high by 4 inches wide, with their thickness and the dimensions of the pole portions in the proportions illustrated in the drawings.

The body is provided with a foot portion at the lower end, which may extend for example about a half inch below'the lower portion 22, this portion being here identified as 20a. This foot portion has a flat bottom, a plane machined surface here identified as 20b adapted to make good magnetic contact with the plane pole surface 131; of the magnetizer, so that a flux path of low reluctance and high flux carrying capabilities is provided into and through the body portion of the block.

The pole portions 2| are of identi al configuration and symmetrically spaced with respect to the center'of a relatively large hole or opening 23 through the block.

As may be best seen in Figures 3 and 5, the magneto rotor comprises a shaft portion here identified as 24 and a cylindrical body or rotor portion proper here identified as 25. the rotor illustrated having four pole portions identified as 25a, 25b, 25c and 25d. The adapter blocks are designed for a given size of rotor. and the pole portions are provided with machined pole faces (sections of'a cylindrical surface), here identifi d as 2m and 22a. These are adapted to lie closely adjacent the pole faces of the rotor when it is between the pole portions of the block, with a very small clearance between these adjacent faces, preferably not over 3AM) of an inch. The inner surfaces of the pole portions are in tially cast in such manner as to be closer to the axis of the openin 23 than illustrated, and are then machined in a step cutter and miller to provide the desired finished cylindrical surfaces and the step or shoulder on each pole portion, here identified as Zlb and 22b which provide stop means for engaging the rotor and properly locating it with respect to the block during charging, as may be best seen in Fi ure 5.

, This figure illustrates the arrangement when the blocks are in operative position and charging a rotor. The blocks are arranged with the flux carrying fingers or pole portions facing toward each other and at least partly interleaved, so that the rotor is surrounded by symmetrically spaced pole faces of alternate polarity. By bringing the blocks toward each other until the shoulders or stop portions'engage the edges of the rotor poles the parts are properly positioned. It. will be noted that in this charging position the: rotor shaft is substantially spaced from any flux.

carrying part of the blocks and, as may be best seen in Figure 3, the pole portions of opposite blocks are sufficiently narrow (in relation to the rotor diameter) to be spaced from each other many times the spacing between the pole faces and rotor poles. Similarly, as may be best seen in Figure 5,- the stop means provided by the shoulders results in spacing of the ends of the pole portions a substantial distance from the opposite block face. This, together with the provision of the foot spacing the pole portions well above the magnetizer pole faces, results in a construction and arrangement concentrating flux energy through the rotor poles and allowing substantially no flux leakage through other paths. This not only results in the maximum rotor magnetization for a given magnetizer strength, but also prevents magnetizing of the shaft (if of magnetic material) and other undesired stray magnetizations.

The shoulders Zlb and 22b should preferably be quite shallow, if of the same magnetic material as the block illustrated, to prevent entry of too much flux from the side rather than the periphery of the rotor. I contemplate providing blocks for handling almost all conventional fourpole rotors from a single casting by machining the pole portion openings of appropriate sizes, but it will be understood that sleeves or other inserts, either as permanent parts of the blocks or as replaceable parts can be used to handle different sized rotors. Similarly, the stop means may be provided by non-magnetic means if desired, as a brass sleeve, or entry of flux from the side edge of the rotor minimized by the use of a spacer washer of fiber or other non-magnetic material.

One of the most important features' of my adapter blocks is location of the pole portions or fingers with their plane at an angle of 45 to the plane of the foot portion of the device, as may be best seen in Figure 3. This not only provides greater flux carrying capacity in the pole portions for a given adapter block size, but also has the very great advantage of enabling a single casting, in the case of work on a four-pole rotor, to provide the two cooperating'blocks. The same casting provides one block, as the block A, having the plane of its pole portions running from lower left to upper right as the parts are viewed in Figure 3, and at the same time a cooperating block which, because it is facing in the opposite direction, has the plane of its pole portions 2! and 22 running symmetrically from lower right to upper left as viewed in such picture. In addition to its manufacturing convenience, the location of the pole portions at a 45 angle insures complete uniformity of magnetizing and of remnance in the rotor pole portions. Since the pole faces of the portions 2| and 22 would be of a given polarity, as north, and those of the other block of the opposite polarity in the case of a four-pole rotor, the fluxes divide and each rotor pole is subjected to an equal total quantity of flux, the total flux through each rotor pole being the sum of a longer magnetic path and a shorter magnetic path in each case. Rounding of all corners and junctures improves the flux carrying capabilities of the blocks.

It will be understood that, while adapter blocks are illustrated for charging a four-pole rotor, my invention is applicable to the charging of six or eight-pole rotors, or even to rotors with an odd number of poles, although in such cases the blgcks, with their requisite number of pole por tions, would have to be cast and machined independently. It is also to be understood that charging may be done in any conventional manner with these adapter blocks, proceeded if desired by demagnetizing forces. My blocks provide means for getting the magnetic forces in the magnetizer, of whatever characteristic, into the poles of a multi-pole rotor with complete uniformity of distribution of flux and forces, and therefore of remnance, from a simple two-pole magnetizer.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

, 1. An adapter block for charging a multi-pole rotor from a two-pole magnetizer, said block comprising a foot portion with a plane surface adapted to make contact with a pole face of the magnetizer and a body portion having two spaced pole portions projecting therefrom in the same direction generally parallel to said plate foot surface and having spaced confronting pole faces adapted to receive the rotor therebetween; a plane through the longitudinal axes of said two pole portions lying at an angle of forty-five degrees to the plane of said foot portion surface.

2. An adapter block for charging a. multi-pole rotor from a two-pole magnetizcr, said block comprising a main body ortion having extending therefrom a foot portion with a plane surface adapted to make contact with a pole face of the magnetizer, two spaced pole portions extending from the body portion in the same direction generally parallel; to said plane foot surface and having spaced confronting pole facesadapted to receive the rotor therebetween, a plane through the longitudinal axes of said two pole portions lying at an gle of forty-five degreesto the t portion surface, stop means on for engaging the rotor, and an body portion between the pole having a dial et'er substantially greater than that of any shaft to be received.

BENJAMIN ROZETT.

Li EX ERIENCES CITED The following references are of record in the file of this patent:

"FOREIGN PATENTS ing, Mechanical World, Dec. 22, 1944, pages 681-683.

eiving the shaft of the rotor and 

